Pitch indicator



Feb. 9, 1937.

W. J. BLANCHARD n FITCH INDICATOR Filed Oct. 27. 1934 3 Sheets-Sheet 1 vF161.v

IN V EN TOR.

WERNER J. BLANCHARD.

FIG

. Feb. 9, 1937. w. J. BLANCHARD 2,069,991

FITCH INDICATOR Filed oct. 2v, 1934 :s sheets-sheet 2 v INVENToR. WERNERJ'. BLANCHARD.

Feb. 9, 1937. w. J. BLANCHARD 2,069,991

BITCH INDICATOR Filed oct. 27, 1934 s sheets-sheet s `l ATTOR v uINVENTOR. WERNER J'. BLANCHARD` FIGB.

FIG. 6.

Patented Feb. A9, 1937 PITCH INDICATOR Werner J. Blanchard, Kenmore, N.Y., assigner,

by mesne Iassignments, to Curtiss-Wright Corporation, a corporation ofNew York Application October 27, 1934, Serial No. 756,256

. svolaims. `'I'his invention relates to; meansfor indicating the bladepitch for controllable pitch 'aircraft propellers. y

The prior art abounds with controllable pitch propellers of variousforms', wherein the power for changing the pitch of the propeller bladesin operation is derived' either from the rotation of the propelleritself, from hydraulic means, or from a mechanical or electrical motivemeans. 'I'he indicating device of this invention is applicable tocontrollable kpitch propellers of any of these types. An object of theinvention is to provide an indicator Visible to an aircraft pilotv whichwill at all times apprise him of the pitch condition ofhis propeller.

A further object is tov provide an indicator which will indicate changesin propeller pitch at the time such pitchchanges are effected.

A further object is to provide an electrical magnetic pitch indicatingdevice which will be sturdy and positive in operation.

A further object is to provide a unitary pitch indicating device in theform of an instrument of conventional cylindrical shape which may be 251mounted on an aircraft instrumentvpanel, re-

quiring relativelyy simple connectionswith the propeller.

Further objects will be appreciated in reading the annexed specificationand claims, and in viewing the drawings, in which:

Fig. 1 isa Side elevation of the indicating instrument with the casingthereof in section;

Fig. 2 is an axial section through the indicating instrument;

Fig. 3 is a, front elevation of the indicator dial; Figs. 4 and 5 aresections on the lines 4--4 and 5-5 of Fig. 2, respectively;

Fig. 6 is a diagrammatic representation of a controllable pitchpropeller showing the electrical connections between the propeller andthe indicating instrument;

Fig. 7 is a section on the line 'I-l of Fig. 6; and

Fig. 8 is a section on the line 8-8 of Fig. '7. Referring to Fig. 6, Ishow a controllable pitch 4 propeller including a hub I0 having blades II turnable about their own axes therein, each blade being provided atits root with a bevel gear I2 engageable with a bevel gear I3 coaxialwith the propeller shaft. A speed reducing unit I4 drives the gear I3and an electric motor I5 drives the v unit I4, this motor having fieldwindings I6 and I`I,'one of which may be energized to cause forw drotation, and the other energized to cause re erse rotation, of a motorarmature I8. The

armature shaft I9 is provided with an extension operative.

(Cl. 172-126) l 20 formed as a worm, with which a worm'wheel 2| engages.The worm wheel 2I-will thereby be driven at reduced speed with respectto the armature shaft, and may be so calibrated .that the shaft of theworm wheel 2| will turn one revolution 5 for every half degree pitchchange in the blade II. The worm wheel shaft carries a lug 22 adapted towipe on a fixed contact 23 during each revolution thereof. Only duringthis interval is the ratcheting mechanism of the pitch indicator 1o Thelug 22 is electrically grounded,v as shown in Fig. 6, while the contact23 is con-k nected to a contact ring 24' mounted on the propellerhub.Additional contact rings 25 and 26 are provided concentric with the ring24, to which l5 rings the terminals of the motor field windings I6 andII are connected. Brushes 21, 28, and `29, fixed to the aircraft, wipeon the rings 24, 25, and

26, respectively. The brush 2l which functions only in connection withthe pitch indicator, is 20 y connected to a pitch indicator 30 at theterminal 3 I. The brushes 28 and 29 are connected to poles 32 and 33 ofa. double pole, double throw switch 34. An arm. 35 of the switch may beselectively thrown to contact with the pole 32 orthe pole 25 33, and inturn is connected to a battery 36, the

other terminal of which is grounded. Thus, it willbe seen that bythrowing the switch arm 35 to one or the other pole 32 or 33, the motorI5 is energized to change the pitch of the propeller in 30 one or theother direction.

The pitch indicator 30 includes solenoids 3l andI 38, each having oneend thereof connected to the post 3|. The other end of the solenoid 31"is connected to a post 39, while the other end of 35 the solenoid 38 isconnected to a post 40. The posts 39 and 4I] are respectively connectedto posts 4I and 42 of the switch 34, these posts being selectivelyengaged by the switch arm 43 connected to the battery.. The switch arms35 and 40l 43 are, of course, movable together. The solenoid 31 willserve, as will hereinafter be described. to effect increasing pitchindications in conjunction with rotation of the motor` I5, in responseto rotation of the motor I5 to increase' the propeller 45 blade pitch.Such rotation of the motor is initiated by closing the circuit throughthe switch arm 35 and the pole 32. Conversely, when the switch arms 35and 43 contact thevpoles 33 and 42, respectively, the motor I5 will beoperated in 5o reverse direction, and the solenoid 38 will be connectedfor reverse pitch indication upon closure of the indicating circuit bymeansof the lug 22. Referring now to Figs. 1 to 5, inclusive, detailedconstruction of the pitch indicator'is shown. 'I'he 55 solenoids 31 and38, of toroidal form, are mounted respectively on segmental cores 45 and46 anchored in 90 relation to one another by means of a sleeve 41contained within the indicator shell4 48. The centers of the cores 45and 46 are provided with axially aligned bearings 49 and 50 which carrya shaft l on which a segmental armature 52 is fixed. The armature isprovided with'a rod 53 extending forwardly from one edge thereof, and aspring 54, anchored to the sleeve 41 at 55, has opposed arms which bearupon the sides of the rod. A stop 56 serves to hold the upper ends ofthe arms of the spring 54 in spaced relation, while the spring arms areformed to bear upon the rod 53 to hold it and the armature in a centralposition between the solenoid cores 45 and 46. If the coil 31 isenergized, magnetic flux induced in the core 45 will tend to draw thearmature in a. clockwise direction, as shown in Fig. 4, and uponde-energizationof said coil, the armature of the spring 54 will returnthe armature to its central position. Similarly, energization of thecoil 38 will magnetically energize the core 46 to draw the armature inan anti-clockwise direction, as shown in Fig. 4, and upon cessation ofthe flow of current, the armature will be returned to its centralposition.

'I'he forward end of the rod 53 carries oppositely vfacing pawls 51 and58, these pawls being pivotally mounted on the rod, and being providedwith a spring 59 urging them downwardly. Coaxial with the shaft 5|, ashaft 60 is mounted in the shell 48 on a bearing 6|, this shaft 68carrying a pair of axially spaced toothed wheels 62 and 63 engagedrespectively by the pawls 51 and 58. The

forward end of the shell 48 is provided with a` dial 64 on which indiciaare inscribed to indicate degrees of propeller pitch. The shaft 60carries a hand 65 adapted to register over the dial. -The toothed wheels62 and 63 are formed with oppositely facing teeth. If one of thesolenoids is ener- Anoid is energized, the pawl 51 will drive thetoothed wheel 62 to the left, to effect pitch decreasing indication uponthe dial.

A shield 66 is provided concentric with the shaft 60, over the wheels 62and 63, and has slots 61 and 68 through which the pawls 51 and 58respectively p'ass. The slots are so formed that when the pawls areoscillated to the right, the pawl 51 will ride up on the edge of theshield to disengage the wheel 62, permitting rotationthereof to theright. Similarly, when the pawls are oscillated to the left, the pawl 58will ride up on the shield to permit driving of the wheel 62 to theleft, releasing the pawl 58 from the Wheel 63.

A ball click 69 is carried by the shell 48 to resiliently engage both ofthe wheels 62 and 63, to

' assist in retaining them in xed position unless they are definitelymoved therefrom by the action of the pawls.

Although I have shown the pitch` indicator coordinated with anelectrically controlled controllable pitch propeller, wherein the switch34 serves to operate both the pitch controlling means and the pitchindicating means, it is apparent that the means for changing propellerpitch maybe other than that'shown, while the device of this inventionmay be readily coordinated therewith. In any controllable pitchpropeller, some control element will be provided which will be movablein one direction to increase the pitch, and in the opposite direction todecrease the pitch. Obviously, that portion of the switch 34 comprisingthe arm 43 and the contacts 4I and 42 may be combined with suchcontrolling element to make the proper connections for actuation of thepitch indicator.

While I have described my invention in detail l in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modifications and changes.

I claim as my invention:

1. An indicating instrument comprising an indicating shaft carrying apointer and a toothed ratchet wheel, a fixed segmental shield concentricwith and embracing part of said wheel, a member oscillatable relative tosaid Wheel, oppositely facing pawls carried by said member, saidvpawlsin their normal position lying close to the ends of the segmental shieldand engag-y ing teeth of said ratchet wheel, and means to oscillate saidmember in either direction from said normal position, one said pawl,upon suchoscillation, engaging and rotating said ratchet wheel, and theother pawl being raised from wheel engagement by said segmental shield.

2. An indicating instrument comprising an indicating shaft carrying atoothed ratchet wheel, a member oscillatable from a mid position toeither side of said mid position, oppositely facing pawls each pivotedto said member for movement into and out of engagement with said ratchetwheel, one said pawl, upon oscillation of said member from its neutralposition being adapted to engage and move said ratchet wheel, and

a shield for raising the other pawl from wheel I' facing pawls carriedby said armature, a ratchetv wheel coaxial with said coils with whichsaid pawls are normally engaged, and means t'o disengage the trailingone of said pawls from said Wheel upon oscillation of said armature fromsaid normal position.

WERNER J. BLANCHARD.

